55 ILCS 5/2-2002
Whenever the county board shall create a new town, or change the name of an existing town, the proceedings in giving a name to such town, or changing the name of an existing town, shall be as follows: The proposed name to be given to such new town, or existing town, shall be filed in the office of the Secretary of State, there to be retained for at least one year; and the Secretary of State, at any time after the filing of such proposed name, shall, upon application of said board, grant his certificate stating that such proposed name, from information appearing in his office, has not been adopted by any city, town, village or municipal corporation in this State; which certificate must be obtained by said board before any action whatever shall be taken by said board toward making such change of name; and all proceedings instituted in any court or other place, under a name changed, without complying with the provisions of this section, shall be held to be void and of no effect. If such name has been adopted elsewhere in this State, the Secretary of State shall so notify the board, whereupon another name shall be filed in his office, which shall there remain in like manner as hereinbefore provided, and the certificate shall be issued by the Secretary of State immediately after such filing, stating that such name has not been elsewhere adopted; whereupon said board may proceed to make such change of name, and not before; and all proceedings pending, and all rights and privileges acquired in the name of such town, by such town, or by any person residing therein, shall be secured to such town or person, and such proceedings continued to final consummation in such name, the same as though the same had not been changed.
55 ILCS 5/2-2002